Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Activities:
Net earnings	$ 107,949	$ 118,736	$ 321,435	$ 344,397
Adjustments to reconcile net earnings to net cash from operating activities:
Provision for losses on accounts receivable	1,321	134	2,461	995
Deferred income tax (benefit) expense	(1,439)	(7,611)	2,342	13,312
Excess tax benefits from stock plans	(107)	0	(239)	(1,846)
Stock compensation expense	10,476	10,919	34,264	32,489
Depreciation and amortization	11,882	11,475	34,853	34,424
Other	11	2	41	115
Changes in operating assets and liabilities:
(Increase) decrease in accounts receivable	(58,279)	2,466	6,087	18,910
Increase (decrease) in accounts payable and accrued expenses	38,070	(19,622)	74,148	3,311
Increase (decrease) in income taxes payable, net	7,197	19,978	(16,612)	4,110
Increase in other current assets	(1,395)	(3,801)	(2,089)	(1,419)
Net cash from operating activities	115,686	132,676	456,691	448,798
Investing Activities:
Purchase of short-term investments	0	0	(54)	(47,008)
Proceeds from maturities of short-term investments	0	38,788	17	79,084
Purchase of property and equipment	(12,659)	(9,546)	(39,973)	(31,903)
Other, net	1,617	(2,666)	5,509	(2,482)
Net cash from investing activities	(11,042)	26,576	(34,501)	(2,309)
Financing Activities:
Proceeds from issuance of common stock	57,522	54,606	147,645	114,701
Repurchases of common stock	(101,690)	(209,970)	(268,097)	(415,475)
Excess tax benefits from stock plans	107	0	239	1,846
Dividends paid	0	0	(73,000)	(68,781)
Distributions to noncontrolling interest	0	0	0	(857)
Net cash from financing activities	(44,061)	(155,364)	(193,213)	(368,566)
Effect of exchange rate changes on cash and cash equivalents	1,853	(20,932)	5,927	(36,347)
Increase (decrease) in cash and cash equivalents	62,436	(17,044)	234,904	41,576
Cash and cash equivalents at beginning of period	980,264	985,727	807,796	927,107
Cash and cash equivalents at end of period	1,042,700	968,683	1,042,700	968,683
Taxes Paid:
Income taxes	$ 58,696	$ 60,374	$ 205,049	$ 190,024